Diffraction Gratings

A different grating has numerous tiny slits, equally spaced A different grating has numerous tiny slits, equally spaced. It separates white light into its component colors just as a double slit would. When a sin = n , light of wavelength  will be reinforced at an angle of . Since different colors have different wavelengths, different colors will be reinforced at different angles, and a prism-like spectrum can be produced.

Diffraction Gratings Note, though, that prisms separate light via refraction rather than diffraction. The pic on the left shows red light shone through a grating. The CD acts as a diffraction grating since the tracks are very close together (about 625/mm).

A diffraction grating is the tool of choice for separating the colors in incident light. When there is a need to separate light of different wavelengths with high resolution, then a diffraction grating is most often the tool of choice. This "super prism" aspect of the diffraction grating leads to application for measuring atomic spectra in both laboratory instruments and telescopes.

When light of a single wavelength , like the 632 When light of a single wavelength , like the 632.8nm red light from a helium-neon laser at left, strikes a diffraction grating it is diffracted to each side in multiple orders. Orders 1 and 2 are shown to each side of the direct beam. Different wavelengths are diffracted at different angles, according to the grating relationship.